Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capac...Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.展开更多
In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing ...In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing this issue without altering the surface morphology or interfering with optical behavior of flammable materials poses a substantial challenge.Herein,we present a transparent,low thickness,ceramifiable nanosystem coating composed of a highly adhesive base(poly(SSS1-co-HEMA1)),nanoscale layered double hydroxide sheets as ceramic precursors,and supramolecular melamine di-borate as an accelerator.We demonstrate that this hybrid coating can transform into a porous,fire-resistant protective layer with a highly thermostable vitreous phase upon exposure to flame/heat source.A nanosystem coating of just~100μm thickness can significantly increase the limiting oxygen index of wood(Pine)to 37.3%,dramatically reduce total heat release by 78.6%,and maintain low smoke toxicity(CIT_G=0.016).Detailed molecular force analysis,combined with a comprehensive examination of the underlying flame-retardant mechanisms,underscores the effectiveness of this coating.This work offers a strategy for creating efficient,environmentally friendly coatings with fire safety applications across various industries.展开更多
To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack ceme...To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO4-SiO2 compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO4 and the volatilization of SiO2 protection layer.展开更多
C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the...C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.展开更多
To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method....To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi2/ZrO2-MoSi2 coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO4, which improves the stability of the coating at high temperatures.展开更多
基金financially supported by the National Natural Science Foundation of China(No.12304077)the Natural Science Foundation of Science and Technology Department of Sichuan Province(No.23NSFSC6224)+3 种基金Sichuan Science and Technology Program(No.2024NSFSC0989)the Key Laboratory of Computational Physics of Sichuan Province(No.YBUJSWL-YB-2022-03)the Material Corrosion and Protection Key Laboratory of Sichuan Province(No.2023CL14 and No.2023CL01)the National Innovation Practice Project(No.202411079005S).
文摘Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.
基金the financial support from the National Natural Science Foundation of China(524B2168,U22A20149,52173081,and 52273275)。
文摘In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing this issue without altering the surface morphology or interfering with optical behavior of flammable materials poses a substantial challenge.Herein,we present a transparent,low thickness,ceramifiable nanosystem coating composed of a highly adhesive base(poly(SSS1-co-HEMA1)),nanoscale layered double hydroxide sheets as ceramic precursors,and supramolecular melamine di-borate as an accelerator.We demonstrate that this hybrid coating can transform into a porous,fire-resistant protective layer with a highly thermostable vitreous phase upon exposure to flame/heat source.A nanosystem coating of just~100μm thickness can significantly increase the limiting oxygen index of wood(Pine)to 37.3%,dramatically reduce total heat release by 78.6%,and maintain low smoke toxicity(CIT_G=0.016).Detailed molecular force analysis,combined with a comprehensive examination of the underlying flame-retardant mechanisms,underscores the effectiveness of this coating.This work offers a strategy for creating efficient,environmentally friendly coatings with fire safety applications across various industries.
基金Projects(51221001,50972120)supported by the National Natural Science Foundation of ChinaProject(73-QP-2010)supported by the Research Fund of the State Key Laboratory of Solidification Processing of Northwestern Polytechnical University,ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO4-SiO2 compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO4 and the volatilization of SiO2 protection layer.
基金Projects(51272213,51221001)supported by the National Natural Science Foundation of ChinaProject(73-QP-2010)supported by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)Project(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.
基金Projects(51221001,51222207)supported by the National Natural Science Foundation of ChinaProject(090677)supported by the Program for New Century Excellent Talents in University of ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi2/ZrO2-MoSi2 coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO4, which improves the stability of the coating at high temperatures.
